Apparatus for changing the position of the web in structural shape rolling

ABSTRACT

An apparatus for repositioning the web of a rolled structural shape such as an H-beam or I-beam in which the web spans between two flanges. The horizontal rolls of the mill stand are individually adjusted by computer based upon a measurement of the web profile upstream of the mill stand along a conveyor for the workpiece so that the rolling gap is located centrally between the upper and lower flange edges notwithstanding the fact that the web may have originally been off-center.

FIELD OF THE INVENTION

[0001] Our present invention relates to an apparatus for changing the position of the web in structural shape rolling and, more particularly, in rolling stands in which the web of a structural shape is rolled by means of horizontal rolls of the rolling mill.

BACKGROUND OF THE INVENTION

[0002] In the rolling of structural shapes, especially in universal mills but also in mills in which the flanges and webs are rolled by pairs of rolls in the mill stand otherwise, it is important that the median plane of the web of the structural shape be centered between the two edges of the flanges and therefore not be offset from the center between these edges.

[0003] When reference is made here to a structural shape having a web, it will be understood that the reference is primarily to I-beams, H-beams and like structural shapes, also referred to as profiles, which have flanges bridged by a web and in which the two flanges have opposite edges, referred to as the upper and lower edges in the case of an H-beam and in the case where either an I-beam or an H-beam is rolled in a conventional universal mill with the web being rolled between the horizontal rolls of the mill stand.

[0004] The horizontal roll pair generally has its axes lying in a common vertical plane and the mill can have vertical roll pairs provided for rolling the flanges.

[0005] The roll gap in a universal mill of this type cannot be adjusted without difficulty during the rolling process to reposition the web of, for example, an H-beam workpiece whose horizontal longitudinal median plane does not always coincide with a plane through the centers between the upper and lower flange edges.

[0006] In practice it is not uncommon for the longitudinal median plane to be offset from the enter lines of the flanges, i.e. the lines equidistant from the upper and lower flange edges. The offcenter location of the web can result from the rolling of the flanges which therefore can have different widths on different sides of the web, especially since the flange rolling usually precedes the rolling of the web between the horizontal rolls.

[0007] The structural shapes, more particularly, are usually initially engaged by the vertical rolls at the outer surfaces of the flanges and only later by the horizontal rolls engaging the inner sides of the flanges and the web with the consequence that the contact of the vertical rolls with the flanges can vary the flange sides relative to the location of the web and thus contribute to an offcenter location thereof.

[0008] Apart from proposals for positioning the rolls at the outset to take into consideration the possibility that an offset may occur and therefore counteract the offset and for controlling the forces with which the rolls attack the workpiece (DE-AS 1 960 891) as a way of correcting for possible offset, there have been numerous proposals for correcting the offset by lateral and height adjustment of guides for the workpiece in and into the rolling gap (DE-OS 2 457 217). In addition, height-adjustable and swingable roller conveyors have been proposed to feed the workpiece into the rolling gap in a correct position to achieve centering of the web. While these techniques are capable of influencing the web position at the outlet side of the mill, systems for pivoting, lifting or dropping the conveyors or guide elements are of complex and expensive construction and are not always capable of satisfactorily centering the median plane of the web. The web position is also influenced by the roll diameter, by roll wear and by like parameters over which there is little control and which cannot be taken into consideration with earlier approaches. In fact, because of factors like roll wear and differences in roll size, it is not uncommon to require roll shimming for exact positioning of the median plane of the web and such shimming requires manual intervention, usually a number of times in successive approximations of the proper center of the median plane. Indeed, the process must be repeated until the finish roll profile has the desired median plane position of the web so that even the manual process is expensive, time consuming, and labor intensive. In spite of all such efforts, the results may not be sufficiently precise or satisfactory.

OBJECTS OF THE INVENTION

[0009] It is, therefore, the principal object of the present invention to provide an improved apparatus for centering the longitudinal median plane of a web in the rolling of structural shapes whereby drawbacks of earlier systems are avoided.

[0010] Another object of this invention is to provide an apparatus for the purposes described which will permit the longitudinal median plane of the web of a structural shape to be centered with greater precision than has heretofore been the case in a less labor intensive and expensive manner.

[0011] Still another object is to provide an improved method of centering the longitudinal median plane of a web during rolling thereof.

SUMMARY OF THE INVENTION

[0012] These objects and others which will become apparent hereinafter are attained with an apparatus which although having a relatively high cost from the technology view point, nevertheless represents a significant advantage in the field by utilizing modern roll stand construction and control techniques to enable the controlled positioning of the web of a rolled structural shape with higher precision than has heretofore been the case and thus for a given position of the longitudinal median plane of the web, represents a less expensive process. The invention does not orient the workpiece, i.e. the structural shape, relative to the rolling gap, i.e. the gap between the horizontal rolls of the mill but rather positions the horizontal rolls vertically and thereby adjusts the gap to suit the workpiece rolled. Positioning of the horizontal rolls is described in Japanese Patent Document 59-193701.

[0013] According to the invention, the position of the web in the structural shape or workpiece is determined by a measuring device provided along the horizontal conveyor and capable of measuring the profile, i.e. the position of the web relative to the upper and lower edges of the flanges. The profile measuring device outputs measurement signals to a computer which calculates the positions of the horizontal rolls for centering the web to be rolled between them between these upper and lower edges of the flanges and adjustments, via suitable effectors or position setting units the upper and lower horizontal rolls for rolling the webs so that its horizontal median plane is properly positioned with respect to the flanges.

[0014] The apparatus, for changing a position of a web of a structural shape workpiece having flanges with upper and lower edges can therefore comprise, according to the invention:

[0015] a horizontal conveyor for conveying the workpiece with the web in a horizontal orientation;

[0016] a mill stand along the conveyor and having an upper horizontal roll and a lower horizontal roll defining a rolling gap for rolling the web;

[0017] a upper roll positioner operatively connected to the upper horizontal roll and a lower roll positioner operatively connected to the lower horizontal roll for vertically positioning the horizontal rolls independently of one another;

[0018] a profile measuring unit along the conveyor upstream of the mill stand and outputting measurement signals representing a shape of the workpiece and an actual position of the web relative to the edges of the workpiece; and

[0019] a computer unit connected to the profile measuring unit and to the upper and lower roll positioners for displacing the rolls in response to the signals to orient the gap midway between the upper and lower edges, thereby repositioning the web upon rolling of the workpiece between the rolls.

[0020] According to the invention, the profile measuring unit can be provided directly on the mill stand. Furthermore, the mill stand can include a profile measuring unit downstream of the rolling gap for measuring the position of the web following rolling between the rolls and whose measurement signals are supplied to a computer unit, which can be the same computer unit mentioned previously, producing setting values for the same pair of rolls when the mill stand is operated in a reversing mode or for a mill stand or set of horizontal rolls so as to automatically reposition the web in that further rolling operation so that it comes closer to a centered position.

[0021] The horizontal conveyor itself may be vertically adjustable for a preliminary control of the position of the oncoming web relative to the horizontal mill rolls.

[0022] When the mill is operated in a reversing drive the profiled measuring units can produce measurement signals which vary the presence of the horizontal rolls as a function of the direction of travel of the workpiece through the gap and thus separately as a function of the rolling direction.

[0023] The invention allows, utilizing modern mill stands and preferably mill stands which permit shifting of the rolls under load, and profile measuring units which are associated with such mill stands to measure the actual position of the web and based upon mathematical models stored in the computer, to alter the web position on further rolling to accurately obtain a targeted position of the web midway between the upper and lower edges of the flanges. The invention is applicable to continuous or reversing roll units, including so-called compact roll units or mill stands and enables a readjustment for any workpiece shape on a piece basis as fed to the apparatus. The apparatus need not be brought to standstill if there is a change in the position of the web on the overcoming workpiece. The roll positioners may be electromechanically operating roll positioners or eccentric units which may be suitable for the purpose.

BRIEF DESCRIPTION OF THE DRAWING

[0024] The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

[0025]FIG. 1 is a diagrammatic vertical section through a mill stand according to the invention showing the position of the web of a structural shape prior to rolling to reposition the web;

[0026]FIG. 2 is a view similar to FIG. 1 but showing the position during rolling;

[0027]FIG. 3 is a diagram explaining characteristics of the invention; and

[0028]FIG. 4 is an end view of a structural shape illustrating the invention.

SPECIFIC DESCRIPTION

[0029] Referring first to FIG. 4, it will be apparent that a structural shape, also referred to as a profile FP can have a web ST with a longitudinal median plane M-M and can be disposed between two flanges FL and FR. These flanges have upper edges FLO and FRO and lower edges FLU and FRU and, in an ideal case, the median plane M-M will be located midway between the upper and lower edges FLO, FLU and FRO, FRU. The beam shown is a so-called H-beam and the principles are applicable as well to so-called I-beams and other structural shapes having flanges and webs.

[0030] The apparatus involved is shown highly diagrammatically in FIG. 3 and comprises a mill stand 10 and a mill stand 20 which can operate in accordance with the principles of FIGS. 1 and 2. The apparatus includes a conveyor such as the roller conveyor generally indicated at 30, an upstream part of which may be vertically adjustable via the adjusting means 31 to preposition a workpiece, FP before it enters the roll gap of the upstream mill stand. The control system of the invention represented generally at 40, comprises the upstream profile measuring unit 41 which, as shown, is capable of measuring the positions of the upper and lower edges of the flanges and the position of the web and feeding the measuring value signals representing the profile and the position of the web, to the computer 42, which can output signals to a pair of roll positioners 43 and 44 for the upper and lower horizontal roll.

[0031] A second profile measuring unit 45 downstream of the computer similarly measures the values for the roll body and inputs that information to the computer. The roll positioners 47 and 48 of a downstream beam of horizontal rolls can also be set by the computer and, if desired, a third profile measuring unit 49 may provide an input to the computer 42 representing the web position downstream of the second mill. All of the profile measuring units may be part of the respective mill.

[0032] The arrows P, P₁ and P₂ represent rolling directions, the arrow P₁, in particular, indicating a reversing operation of one or both of the mills.

[0033] From FIG. 1 it will be apparent that the upper horizontal roll HO and the lower horizontal roll HU of a reversal mill stand 10 not otherwise illustrated but equipped with vertical rolls VW, for example, define a roll gap WSP for the structural shape which is to be supplied in the direction of arrow P.

[0034] The structural shape FP rests on its lower flange edges, e.g. FRU and rides on the rollers R of the roller conveyor 30. The web ST of the workpiece FP has its web offset somewhat upwardly as will be apparent at the left hand side of FIG. 1, the median plane of that web being represented at M-M. As a result, the distance d1 of the median plane M-M from the upper flange edge FRO is smaller than the distance d2 of that plane from the lower flange edge FRU.

[0035] The upper horizontal roll HO and the lower horizontal roll HU are, prior to the determination of the profile, in the positions shown in dot-dash lines.

[0036] Utilizing the profile measuring unit, as the workpiece reaches the gap and the web encounters the gap, the rolls HO and HU are moved by the roll positioners 43, 44 into the solid line positions shown which repositions the gap as it is rolled (see FIG. 2), so that these webs are located at equal distances d1′ and d2′ from the upper flange edge FRO and the lower flange edge FRU, thereby achieving the desired web reposition.

[0037] The profile measurement following this rolling at 45 can provide a feedback to the computer 42 to guarantee accurate positioning of the web by readjustment of the roll positioners 43 and 44 and/or by setting the roll positioners 47 and 48 and a final measurement at 49 can be used as feedback for the roll positioners 47 and 48. 

We claim:
 1. An apparatus for changing a position of a web of a structural shape workpiece having flanges with upper and lower edges and said web between said flanges, said apparatus comprising: a horizontal conveyor for conveying said workpiece with said web in a horizontal orientation; a mill stand along said conveyor and having an upper horizontal roll and a lower horizontal roll defining a rolling gap for rolling said web; a upper roll positioner operatively connected to said upper horizontal roll and a lower roll positioner operatively connected to said lower horizontal roll for vertically positioning said horizontal rolls independently of one another; a profile measuring unit along said conveyor upstream of said mill stand and outputting measurement signals representing a shape of the workpiece and an actual position of the web relative to said edges of said workpiece; and a computer unit connected to said profile measuring unit and to said upper and lower roll positioners for displacing said rolls in response to said signals to orient said gap midway between the upper and lower edges, thereby repositioning said web upon rolling of said workpiece between said rolls.
 2. The apparatus defined in claim 1, further comprising another profile measuring unit along said conveyor downstream of said rolls and producing measurement signals representing the shape of the workpiece following rolling of said web between said rolls and supplying same to a computer unit.
 3. The apparatus defined in claim 2, further comprising another mill stand along said conveyor having upper and lower horizontal rolls and upper and lower roll positioners operatively connected to the upper and lower horizontal rolls of said other mill stand for varying said web position upon rolling of said workpiece in said other mill stand.
 4. The apparatus defined in claim 1, further comprising means for adjusting the height of said conveyor at least along a segment thereof upstream of said mill stand.
 5. The apparatus defined in claim 1 wherein said mill stand is adapted for reversing operation and said apparatus has profile measuring units providing different measurement signals for differing directions of rolling of said workpiece in said mill.
 6. A method of operating a mill stand for rolling of a structural shape workpiece having flanges with upper and lower edges and a horizontal web between said flanges, said mill stand having an upper horizontal roll and a lower horizontal roll defining a rolling gap for rolling said web, said method comprising the steps of: a) feeding said workpiece along a horizontal conveyor to said gap in a horizontal orientation of said web; b) measuring a profile of said workpiece upstream of said gap and outputting measurement signals representing a shape of the workpiece and an actual position of the web thereof relative to said edges of said workpiece; c) vertically positioning said horizontal roll independently of one another and in response to said measurement signal to orient said gap midway between the upper and lower edges; and d) rolling said web between said horizontal rolls thereby repositioning said web.
 7. The method defined in claim 6 wherein said rolls are displaced to orient said gap as said web approaches said gap.
 8. The method defined in claim 6 wherein said rolls are displaced to orient said gap while said web is in said gap between said rolls.
 9. The method defined in claim 6, further comprising measuring the profile of said workpiece downstream of said gap and adjusting horizontal rolls of a second mill stand downstream of the first-mentioned mill stand to adjust the position of the web of the workpiece as it is rolled in the second mill stand.
 10. The method defined in claim 6, further comprising the step of measuring the shape of the workpiece downstream of said rolls, reversing the direction of travel of said workpiece through said gap between said rolls and controlling the measurement signal positioning said rolls in accordance with the direction of travel of the workpiece through said gap between said rolls. 